FACEBOOK will consider charging users a fee to not receive advertisements based on what they have shared with friends on the social media platform.

Mark Zuckerberg confirmed the contentious strategy to possibly make Facebook users pay for their privacy at today’s Capitol Hill appearance, as he revealed his biggest regret was not acting sooner to stop Russia using his platform to try to influence foreign elections.

Facebook founder Mark Zuckerberg was asked about the contentious plan to make Facebook users pay for their privacy at today’s Capitol Hill appearance.

Senator Bill Nelson asked how Facebook users who did not wish to see targeted ads, such as their favourite type of chocolate, could stop the product placements from flooding their feed.

“Are you actually considering having Facebook users pay for you to not use that information?,” Senator Nelson asked.

“In order to not run ads at all we would need some kind of business model,” Mr Zuckerberg said.

“I am going to have to pay you in order not to send me using my personal information, something that I don’t want?” Senator Nelson said.

“Yes, Senator,” he replied.

“You consider my personally identifiable data the company’s data and not my data, is that it?”, he asked, to which he answered no.

He said that while the ad-free product did not yet exist, the only way for Facebook to remain a viable business was to run advertisements or charge for use of the site, and stepped back from his previous pledge that the platform would always be free.

“There will always be a version of Facebook that is free,” Mr Zuckerberg said.

Facebook shares start to rise after Mark Zuckerberg started to testify. Picture: SuppliedSource:Supplied

Facebook shares began to steadily climb on the Nasdaq after Mr Zuckerberg began to speak around 3pm (5am AEST), lifting by more than 4 per cent.

Senator Nelson said the privacy breach that sparked today’s hearing was not acceptable.

“I am going to cut to the chase, if you and other social media companies do not get your act together none of us going to have any privacy anymore,” he said.

Listing the data points held by Facebook of its users, he said: “Facebook has a responsibility to protect this personal information”.

Some questioning got personal, with one senator asking: “As a dad do you worry about social media addiction as a problem for American teens?”

“This is certainly something that I think any parent thinks about…,” he said.

“At Facebook specifically, I view our responsibility as not just building services that people like but building services that are good for people as well..”

“Like any tool, there are good and bad uses of it.”

Senator Dick Durbin had earlier asked a series of questions that drove home the point that today’s hearing is at its core about privacy.

“What hotel did you say at last night?” he asked, followed by whether the CEO would be happy to share the content of his private messages over the past week.

To those questions, he answered no: “not in this public forum”.

Mr Zuckerberg added that “everyone should have control over how their information is used”.

Mr Zuckerberg, wearing a blue suit and tie, sat still and showed little expression on his face, quietly nodding a greeting at some of the senators before he started his testimony.

He listened to more than 30 minutes of opening statements before reading an abridged version of his pre-prepared introduction.

Facebook CEO Mark Zuckerberg arrives to testify before a joint hearing of the Commerce and Judiciary Committees on Capitol Hill. Picture: APSource:AP

The first speaker was Senator John Thune, Senate Commerce Committee Chairman, who said Facebook was an “American dream” that was threatening to turn into a “nightmare”.

“Facebook’s incredible reach is why we are here today,” he said.

“One reason that so many people are worried about this incident is because of what it says about how Facebook works.

“How will you protect user’s data, how will you inform users about the changes that you are making and how do you intend to proactively stop harmful conduct instead of being forced to respond to it?,” he said.

Senator Thune asked, given Facebook has responded to repeated scandals by apologising, why “after more than a decade of apologies ... today’s apology is different”.

Senator Orrin Hatch said today’s hearing was “the most intense public scrutiny of a tech company” he had seen since the Microsoft antitrust hearings he convened in the late 1990s.

Mr Zuckerberg said the company would probe “every single app that had access to a large amount of information” on the platform.

“We believe that we’re going to be investigating many apps — tens of thousands of apps,” he said.

“And if we find any suspicious activity we’re going to conduct a full audit of those apps to understand how they’re using their data and if they’re doing anything improper.”

Senator Richard Blumenthal’s questions revolved around the Russian born app-developer Aleksandr Kogan, who sold the Facebook data to Cambridge Analytica.

Mr Zuckerberg has repeatedly said Mr Kogan deceived the company when he harvested the data of at least tens of millions of users. But Senator Blumenthal waved a copy of the terms of service that Mr Kogan used, and said those terms included commercial use of the data.

“Facebook was on notice that he could sell that user information,” Senator Blumenthal said, adding that the site had been “heedless and reckless”.

He also said Facebook had violated the Federal Trade Commission by not reporting the breach when they became aware of it in 2015.

“We’ve seen the apology tours before. You have refused to acknowledge even an ethical violation to report this violation of the FTC consent decree,” Senator Blumenthal said.

“My reservation about your testimony today is that I don’t see how you can change your business model unless there are specific rules of the road. Your business model is to maximise profit over privacy. I have no assurance that these kids of vague commitments are going to produce actions.”

The most fired up questioning came from Republican Senator Ted Cruz, and what he described as anti-conservative political bias on Facebook, after Mr Zuckerberg defended it as a “platform for all ideas”.

“There are a great many Americans who I would say are deeply concerned that Facebook and other tech companies are engaged in a pervasive pattern of bias and political censorship,” said Senator Cruz, a fundamentalist christian who challenged Donald Trump as a far right candidate for the Republican nomination in the 2016 election race.

He cited reports that the platform had suppressed conservative media outlets and pointed to a recent controversy where two Trump supporters, video-blogging sisters known as Diamond and Silk, were kicked off the platform after being described as “unsafe to the community”.

Senator Cruz also said Facebook blocked a post from a Fox News journalist and also suppressed “over two dozen” Catholic pages. He asked Mr Zuckerberg if he knew of any left leaning users who were blocked and Mr Zuckerberg said he did not know of any.

“To a great many Americans, that appears to be a pervasive pattern of political bias,” Senator Cruz said.

Mr Zuckerberg said: “I understand where that concern is coming from, because Facebook and the tech industry are located in Silicon Valley, which is an extremely left leaning place.”

“This is actually a concern that I have, and that I try to root out at the company, is making sure that we don’t have any bias in the work that we do.

“I think it is a fair concern that people would at least wonder about.”

FACEBOOK ASSISTING SPECIAL COUNSEL ON RUSSIA

Mr Zuckerberg said Facebook was co-operating with Special Counsel Robert Mueller’s investigation into Russian attempts to interfere in the 2016 US election.

He said he was not sure if any of his staff had been subpoenaed but that they were talking to investigators. He said he personally had not been interviewed and would not elaborate further.

“Our work with the special counsel is confidential,” he said.

Mark Zuckerberg said Facebook is assisting Robert Mueller’s probe into Russian meddling in the 2016 US election. Picture: APSource:Supplied

Mr Zuckerberg opened up on what he said was one of his biggest mistakes as Facebook CEO.

“One of my greatest regrets in running the company is that we were slow in identifying the Russian information operations in 2016,” he said.

“There are people in Russia whose job it is, it to try to exploit our systems,” he said.

“So this is an arms race.”

ZUCKERBERG CRAMMED BEFORE HEARING

Mr Zuckerberg has been cramming with image consultants in preparation for the testimony, the final leg in a week-long apology tour after it was revealed 87 million accounts were breached by a shadowy political firm.

The appearance is Mr Zuckerberg’s first in Washington despite numerous calls for him to testify before congress. In the past Facebook has sent lawyers in his stead.

Mr Zuckerberg is facing scrutiny inside a crowded hearing room from 44 senators who each have four minutes to ask questions.

The high stakes sitting has implications for Facebook’s share price and the future of the company, with a poor performance possibly inviting further government scrutiny and even regulation of his company.

Some of what Mr Zuckerberg will say was contained in an introductory statement released yesterday, in which he begins by defining the company he founded in 2007 as an “idealistic” and “optimistic” platform to connect people.

“But it’s clear now that we didn’t do enough to prevent these tools from being used for harm as well,” he will say.

“That goes for fake news, foreign interference in elections, and hate speech as well as developers and data privacy.

“We didn’t take a broad enough view of our responsibility, and that was a big mistake.

“It was my mistake and I’m sorry. I started Facebook, I run it, and I’m responsible for what happens here.”

It comes as Facebook — which has 2 billion users worldwide — was to begin issuing warnings to the 300,000 Australians swept up in the Cambridge Analytica scandal, telling them their personal information was harvested and sold.

They are among more than 87 million Facebook users whose data was used to try to influence foreign elections.

The messages revealed for the first time what information was taken from them. In most cases this was their public profile, including their date of birth, location and likes, according to the message.

However, the messages did not include an apology to users, rather a statement on the importance of keeping their data safe.

Mr Zuckerberg faces a hostile reception on Capitol Hill, where politicians will drill down on what the network knew about the breaches and also why it did not tell users when it first learned of them in 2015.

Some in Washington are framing the breach as an opportunity to push for increased regulation of the web.

“The message that I wanted to convey to him (is) that if we don’t rein in the misuse of social media, none of us are going to have any privacy anymore,” said Florida Senator Bill Nelson after meeting with Mr Zuckerberg.

“My sense is that he takes this seriously because he knows there will be a hard look at regulation.”